Add ldlinux.c32 to boot ISO for virtual media

To create a boot ISO for netboot with virtual media boot, ldlinux.c32
is required for syslinux 5.00 or later. This patch copies ldlinux.c32
in building ISO from general paths by default. A new configuration
parameter [DEFAULT]/ldlinux_c32 is added for another distribution
or feature changes.

Change-Id: I55229f0ab37e657b7668dd4fe402fe6b5a6cda40
Closes-Bug: #1694645

etc/ironic/ironic.conf.sample

@@ -314,6 +314,12 @@
 # Template file for grub configuration file. (string value)
 #grub_config_template = $pybasedir/common/grub_conf.template
 
+# Path to ldlinux.c32 file. This file is required for syslinux
+# 5.0 or later. If not specified, the file is searched in
+# general paths, "/usr/lib/syslinux/modules/bios/ldlinux.c32"
+# and "/usr/share/syslinux/ldlinux.c32". (string value)
+#ldlinux_c32 = <None>
+
 # Run image downloads and raw format conversions in parallel.
 # (boolean value)
 #parallel_image_downloads = false

ironic/common/images.py

@@ -184,6 +184,9 @@ def create_isolinux_image_for_bios(output_file, kernel, ramdisk,
     """
     ISOLINUX_BIN = 'isolinux/isolinux.bin'
     ISOLINUX_CFG = 'isolinux/isolinux.cfg'
+    LDLINUX_SRC_DIRS = ['/usr/lib/syslinux/modules/bios',
+                        '/usr/share/syslinux']
+    LDLINUX_BIN = 'isolinux/ldlinux.c32'
 
     options = {'kernel': '/vmlinuz', 'ramdisk': '/initrd'}
 
@@ -193,6 +196,20 @@ def create_isolinux_image_for_bios(output_file, kernel, ramdisk,
             ramdisk: 'initrd',
             CONF.isolinux_bin: ISOLINUX_BIN,
         }
+
+        # ldlinux.c32 is required for syslinux 5.0 or later.
+        if CONF.ldlinux_c32:
+            ldlinux_src = CONF.ldlinux_c32
+        else:
+            for directory in LDLINUX_SRC_DIRS:
+                ldlinux_src = os.path.join(directory, 'ldlinux.c32')
+                if os.path.isfile(ldlinux_src):
+                    break
+            else:
+                ldlinux_src = None
+        if ldlinux_src:
+            files_info[ldlinux_src] = LDLINUX_BIN
+
         try:
             _create_root_fs(tmpdir, files_info)
         except (OSError, IOError) as e:

ironic/conf/default.py

@@ -199,6 +199,12 @@ image_opts = [
                default=os.path.join('$pybasedir',
                                     'common/grub_conf.template'),
                help=_('Template file for grub configuration file.')),
+    cfg.StrOpt('ldlinux_c32',
+               help=_('Path to ldlinux.c32 file. This file is required for '
+                      'syslinux 5.0 or later. If not specified, the file is '
+                      'searched in general paths, '
+                      '"/usr/lib/syslinux/modules/bios/ldlinux.c32" and '
+                      '"/usr/share/syslinux/ldlinux.c32".')),
 ]
 
 img_cache_opts = [

ironic/tests/unit/common/test_images.py

@@ -549,9 +549,9 @@ class FsImageTestCase(base.TestCase):
     @mock.patch.object(utils, 'tempdir', autospec=True)
     @mock.patch.object(utils, 'execute', autospec=True)
     @mock.patch.object(images, '_generate_cfg', autospec=True)
-    def test_create_isolinux_image_for_bios(
+    def _test_create_isolinux_image_for_bios(
             self, gen_cfg_mock, execute_mock, tempdir_mock,
-            write_to_file_mock, create_root_fs_mock):
+            write_to_file_mock, create_root_fs_mock, ldlinux_path=None):
 
         mock_file_handle = mock.MagicMock(spec=file)
         mock_file_handle.__enter__.return_value = 'tmpdir'
@@ -575,6 +575,8 @@ class FsImageTestCase(base.TestCase):
             'path/to/ramdisk': 'initrd',
             CONF.isolinux_bin: 'isolinux/isolinux.bin'
         }
+        if ldlinux_path:
+            files_info[ldlinux_path] = 'isolinux/ldlinux.c32'
         create_root_fs_mock.assert_called_once_with('tmpdir', files_info)
         gen_cfg_mock.assert_called_once_with(params,
                                              CONF.isolinux_config_template,
@@ -587,6 +589,22 @@ class FsImageTestCase(base.TestCase):
             '4', '-boot-info-table', '-b', 'isolinux/isolinux.bin',
             '-o', 'tgt_file', 'tmpdir')
 
+    @mock.patch.object(os.path, 'isfile', autspec=True)
+    def test_create_isolinux_image_for_bios(self, mock_isfile):
+        mock_isfile.return_value = False
+        self._test_create_isolinux_image_for_bios()
+
+    def test_create_isolinux_image_for_bios_conf_ldlinux(self):
+        CONF.set_override('ldlinux_c32', 'path/to/ldlinux.c32')
+        self._test_create_isolinux_image_for_bios(
+            ldlinux_path='path/to/ldlinux.c32')
+
+    @mock.patch.object(os.path, 'isfile', autspec=True)
+    def test_create_isolinux_image_for_bios_default_ldlinux(self, mock_isfile):
+        mock_isfile.side_effect = [False, True]
+        self._test_create_isolinux_image_for_bios(
+            ldlinux_path='/usr/share/syslinux/ldlinux.c32')
+
     @mock.patch.object(images, '_umount_without_raise', autospec=True)
     @mock.patch.object(images, '_create_root_fs', autospec=True)
     @mock.patch.object(utils, 'tempdir', autospec=True)

releasenotes/notes/bug-1694645-57289200e35bd883.yaml

@@ -0,0 +1,14 @@
+---
+fixes:
+  - |
+    Fix a bug that netboot is unavailable with virtual media boot in an
+    environment using syslinux 5.00 or later such as Ubuntu 16.04. This is
+    caused by a change in syslinux that ldlinux.c32 is required for creating
+    boot ISO. This file is searched in the following general paths:
+
+      * /usr/lib/syslinux/modules/bios/ldlinux.c32
+      * /usr/share/syslinux/ldlinux.c32
+
+    This path can be set with the configuration parameter
+    ``[DEFAULT]/ldlinux_c32`` for another distribution or for a case where the
+    path is changed with future update.